Lateral control for airplanes



March 27, 1928.

A. H. G. FTOKKER LATERAL CONTROL FOR AIRPLANES Filed Aug. 26. 1922lnvenlor AMI/may ft 61/?K 142w a Patented Mar. 2?, 1928.

UNIT-an STATES P T '11 N ANTHONY H. G. IOKKER, OF AMSTERDAM,NETHERLANDS, ASSIGNOR TO ATLANTIC AIRCRAFT CORPORATION, A CORPORATION OFNEW JERSEY.

LATERAL CONTROL FOR AIBPLANES.

Application filed August 26, 1922, Serial No. 584,595, and in GermanyMarch 22, 1921.

The'present invention relates generally to improvements in airplanes andis more especially directed to a method and means of effecting lateralcontrol thereof in flight.

It iswell known that the actuation of the ailerons, by means of whichthe air flow is modified and the camber of the wings andthe angle ofincidence altered to give greater or less lift in maintaining lateralbalance in the usual type of airplane, causes the airplane to deviatefrom its straight line of flight. This follows from the differential ofresistance which is set up when one aileron is lowered and the otherraised, the increased resistance against the lowered aileron tending toproduce a turning movement ofthe airplane from its line of flight. Tocorrect or overcome this tendencyof the present types of airplanes tochange their direction of flight on the actuation of the ailerons, it isnecessary to simultaneously operate the rudder to the right or left asthe case may be. Obviously, the necessity of functioning the directionalcontrol or rudder in conjunction with the lateral control, if a straightline of flight is to be maintained by the airplane, is a serious defectin airplane construction as at present constituted. This is especiallytrue, when the airplanes are being operated by novices or inexperiencedaviators.

The general object of the present invention is to provide a simplemethod and means to obviate the necessity of operating the rudder ordirectional control of the airplane, when the ailerons or flaps areactuated, in order that a straight line of flight maybe maintained, thusenabling the aviator to operate the airplane with a minimum of effortwith a consequent increase in the factor of safety.

More specifically, it is the object of my invention-to provide a methodof effecting the practical equalization of the resistance of theailerons when normally actuated, the elimination of the differential inthe resistance of the ailerons overcoming the tendency of the airplaneto turn from its straight line of flight, thereby rendering theoperation of the rudder or directional control in conjunction. with thelateral control unnecessary.

A further object of my invention is to provide a means of practicing myinvention,

which is subject to general application in airplane construction, thuspermitting its incorporation in existing structures at .a minimum ofcost.

Other objects and advantages of my invention will become manifest asthe. description proceeds, and I would have it understood that I reserveunto myself all rights to the full range of equivalents, both instructure and uses, to which I may be entitled.

For the purposes of the present disclosure, I have elected to illustrateand describe certain preferred embodiments of means for practicing myinvention. However, my invention may be carried out by other means ormechanisms without departing from the spirit and scope thereof, asdefined by the appended claims.

In the drawings:

Figure 1 is a view in perspective of a fragment of a conventionalairplane wing or aerofoil showing a preferred form of aileron or flapfor attaining the objects of my invention;

Figures 2 and 3 are fragmentary views of the left andright hand ends ofan airplane wing when the lateral control has been actuated to raise theleft hand side of the wing and restore the wing balance;

Figure 4 shows a modified form of aileron for practicing my invention;and

Figure 5 illustrates a type of structure in which the aileron carries abalancing surface spaced therefrom.

Referring now to the drawings in detail, in which like characters ofreference are employed to designate similar parts in the several views,1 indicates an airplane wing of a conventional curvature, the trailingedge of which adjacent to each end is cut-away to provide for themounting of an aileron or flap 2, which is hingedly connected to thewing along the hinge line 3. The right and left hand ailerons areconnected by suitable cables to an actuating element such as a joy stickor a wheel whereby they are simultaneously moved in oppositedirections,- to maintain or restore the equilibrium of the airplane onits longitudinal. axis.

In normal flight, the position of the aile-" rons relative to the wing 1is as shown in and the normal flight of the fit? erably an integral partof the aileron structure, forms a balance for the aileron and is shapedto present a negative angle of incidence at normal flight, the an le ofincidence at which the airplane is ying being the angle between the lineof flight and the chord line of the plane; that is, a straight linedrawn fore-and-aft tangent to the leading and trailing edges of thewing. Therefore, it will be evident that, when the ailerons at theopposite ends of the wing are in the position shown in Figure 1, therespective extensions 4 will neutralize each other plane will in no waybe affected thereb Assuming now, that rom one cause or another, theairplane banks or tendsto ro fate on its longitudinal axis in adirectiontoward the left, it is necessary, in order to restore the balance, toactuate the control to depress the left-hand aileron 2 (shown in Figure2), the right-hand aileron 2' being simultaneously raised (see Figure3). Manifestly, there is an increase in the resistance of the aileronwhich is depressed, but at the same time the resistance'of the extensionl of the left aileron 2 (which rises as the aileron is depressed) isdecreased, resulting in a considerable reduction in the total netincrease in' resistance at the left hand end of thewing. On the otherhand, the resistance of the right aileron 2", which is raised, increasesbut slightly, if any, owing to the well known properties of air fiow'around wing sections, while the resistance of its component extension 4,which is directed downwardly, is greatl increased. It will be seen thatthe functiomng of the balance surfaces 4* and 4 as just described,creates unequal forces in opposite directions about a central verticalaxis intersecting the horizontal axis of the airplane, the resultant ofthese forces having a torque equal to the torque produced by the warpingof the ailerons. The differential in the resistance at the opposite endsof the wing, which is an inherent disadvantage in the actuation of theailerons in airplanes of the present types,

being thus eliminated, there is consequently no tendency of the airplaneto deviate from its path of flight. It follows, therefore, that the useof the directional control, or rudder, in conjunction with the actuationof the lat eral control to enable the aviator to maintain his path .offlight, is unnecessary.

ft is apparent that the relative dimensions of the various parts orsurfaces by means of which my invention may be practiced may be readilydetermined by those skilled in the art, so that when the ailerons areactuated, the resistance at the opposite ends of the wing will be equaland the described results attained.

in the modified structure, shown in Figure it will be observed that theextension 4 of the aileron 2 is twisted or curved towards its forwardedge so that part of it will present a negative angle ofincidence,'wh1le in Figure 5 the balance element'fi is supported abovethe upper surface of the aileron 2 and forward of the hinge line'3. Thisbalance element 6, similar to the elements or exten-. sions heretoforedescribed, is set at a negative angle of incidence, the method offunctioning of the structure shown in these latter figures being thesame as explained with reference to Flgures 1 to 3 inclusive.

From the foregoing description, it will be noted that my inventionissusce tible of incorporation-in any type of airp ane employing ailerons,or flaps, for effecting lateral control, the configuration and size ofthe ailerons and their component balance surfaces being suitable to thestructure in which they are to be used.

What is claimed is:

1. The method of effecting lateral balancing of airplanes having a fixedwing or lifting surface and ailerons hinged to the opposite ends thereofwhich consists in counteracting the effect of the increased resistanceto a depressed aileron at the same end of the wing, and simultaneouslyincreasing the resistance at the other end of the wing to compensate forthe decrease in resistance by the raising of the aileron at such end.

2. An airplane having a fixed lifting surface and ailerons hinged atopposite ends of the trailing edge thereof, each of said ailerons havinga surface disposed at a negative angle of incidence at normal flight,said surfaces, when the ailerons are respectively raised and depressed,being adapted to compensate for the differential in pressure uponthedopposite ailerons when actuated as afore sal 3. An airplane havingfixed lifting surfaces, lateral controlling devices, directional controldevices, and means for compensating for directional disturbance producedby the manipulation of the lateral control devices, said means beingindependent of the direc-= tional control devices.

t. An airplane having fixed lifting surfaces, lateral controllingdevices, directional control devices, and means for compensating fordirectional disturbance produced by the. manipulation of the lateralcontrol devices, said means being independent of thedirectional controldevices and operated by the manipulation of the lateral control devices.5. The method of stabilizing airplanes having fixed lifting surfaceswhich cornprises the creation of unequal forces in opposite directionsabout a central vertical axis, whose resultant has a torque equaling andopposed to the torque about said axis proeeaaoe 6. An airplane having afixed lifting surface and ailerons hinged'at opposite ends of thetrailing edge thereof, each of said ailerons having a surface disposedat a negaface provided with lateral stabilizing de-' vices at itsopposite ends, each of said devices having a conjointly movable surfacenormally disposed at a negative angle of incidence, said surfaces, whenthe stabilizing devices are actuated, being adapted to create unequalforces in opposite directions about a central vertical axis of theairplane, whose resultant has a torque equalling and opposed to thetorque produced by the raising of one stabilizing device and thedepression of the other.'

8. An aileron adapted for hinged connection to the trailing edge of anairplane wing, embodying an integral forwardly directed extension at itsouter end, said extension being curved to present a'negative angle ofincidence at normal flight, and functioning to compensate for thedifferential in resistance set up by the actuation of the ailerons centend ofthe wing or lifting surface, said in the usual manner, which tendsto rotate the airplane on its vertical axis.

9. An airplane having a fixed lifting surface or wing provided withstabilizing devices at its opposite ends, said stabilizing devices beingcapable of actuation to control the movement of the airplane about itslongitudinal axis, each, of said stabilizing devices being formed withan extension disposed at a negative angle of incidence at normal flight,said extensions being adapted to create unequal forces in oppositedirections about a central vertical axis when the stabilizing devicesare respectively raised and depressed, whose resultant has a torqueequaling and opposed to the torque produced by the actuation of thestabilizing devices.

10. Anairplane having a fixed lifting surface and ailerons'hinged atopposite ends thereof adjacent to the trailing edge of said surface,each of said ailerons extending be yond the adjacent end of the liftingsurface and having a forwardly directed portion dis-' posed at anegativeangle of incidence at normal flight, said aileron portions, when theailerons are respectively raised and depressed, being adapted tocompensate for the diflerential in pressure upon the oppositeailerons'produced by the actuation thereof.

11. In an airplanejhaving a fixed wing or lifting surface, thecombination of an aileron movably mounted at each end of said wing orlifting surface and adjacent to the trailing edge thereof, each of saidailerons extending beyond the adjacent end of the wing or liftin surfaceand having a for wardly directe extension, the inner end of which issubstantially parallel to the adjaextension having a downwardinclination so as to present a negative angle of ncidence .in normalflight.

ANTHONY H. G. FOKKER.

